2015-12-01 10:26 GMT+01:00 Sven Van Caekenberghe <[email protected]>: > > > On 01 Dec 2015, at 10:18, Ben Coman <[email protected]> wrote: > > > > On Tue, Dec 1, 2015 at 4:45 PM, Sven Van Caekenberghe <[email protected]> > wrote: > >> I am all for a cleanup, the current situation is confusing. > >> The basic #sum should be fast AND work for empty collections with 0 as > starting element. > > > >> I know why the #anyOne is used, and that use case should be preserved, > but it is less common IMHO. > > > > I'm curious to be learn why? > > How many times have you summed a collection of things, where (1) you could > not start from the number 0 and (2) the operation was #+ ? Me, never, and > if I would need that, I would do an #inject:into: myself. Any counter > examples that occur a lot ? >
wokring with things like Color (Color wheel:10) sum "works" (Color wheel:10) newSum:#yourself " would not work" > > > cheers -ben > > > >> > >>> On 01 Dec 2015, at 09:38, Thierry Goubier <[email protected]> > wrote: > >>> > >>> Hi Max, > >>> > >>> Interesting results... > >>> > >>> replacing the #yourself in newSum: cuts the runtime by a factor of two. > >>> using an [:x | x ] block cost 10% compared to a direct version of sum. > >>> > >>> So the fastest sum is: > >>> > >>> sum > >>> ^ self > >>> inject: > >>> (self ifEmpty: [ ^ 0 ] ifNotEmpty: [ self anyOne > ]) > >>> into: [ :sum :each | sum + each ] > >>> > >>> And > >>> > >>> sum > >>> ^ self sum: [:x | x ] > >>> > >>> is 10% slower. > >>> > >>> And > >>> > >>> sum > >>> ^ self sum: #yourself > >>> > >>> is 100% slower (i.e. x2) > >>> > >>> It may be wise to avoid using #yourself for a block. > >>> > >>> Thierry > >>> > >>> > >>> 2015-12-01 9:17 GMT+01:00 Max Leske <[email protected]>: > >>> Hi guys, > >>> > >>> Collection defines #sum:, #detectSum: and #sumNumbers:, all of which > accomplish the same (in principal) but with subtle differences: > >>> > >>> #sum: > >>> - uses #inject:into: with #anyOne as the injected element and will > thus fail for empty collections > >>> > >>> #detectSum: > >>> - uses “nextValue + sum” instead of “sum + nextValue” which makes it a > lot slower when dealing with large numbers (primitive fails and number > conversion is necessary) > >>> > >>> #sumNumbers: > >>> - same as #sum but doesn’t fail for empty collections. Only good for > numbers though. > >>> > >>> > >>> Benchmarks: > >>> > >>> [ 100 timesRepeat: [ (1 to: 1000000) sum: #yourself ] ] timeToRun 18062 > >>> [ 100 timesRepeat: [ (1 to: 1000000) detectSum: #yourself ] ] > timeToRun 42391 > >>> [ 100 timesRepeat: [ (1 to: 1000000) sumNumbers: #yourself ] ] > timeToRun 18096 > >>> > >>> > >>> > >>> Can we settle for a single implementation? Such as (modified from > #sumNumbers:): > >>> > >>> newSum: aBlock > >>> ^ self > >>> inject: (self > >>> ifEmpty: [ 0 ] > >>> ifNotEmpty: [ self anyOne ]) > >>> into: [ :sum :each | sum + (aBlock value: each) ] > >>> > >>> This implementation combines the best of the three implementations I > think. Benchmark: > >>> > >>> [ 100 timesRepeat: [ (1 to: 1000000) newSum: #yourself ] ] timeToRun > 17955 > >>> > >>> > >>> BTW, there is also the message #sum, which suffers from the same > problem as #sum: (the implementation is basically a copy). #sum could be > implemented as > >>> > >>> sum > >>> ^ self sum: [ :x | x ] > >>> > >>> > >>> As for the name for the new method, I suggest #sum:. > >>> > >>> Cheers, > >>> Max > >>> > >> > >> > > > > >
